Manufacturers of network equipment encounter increasingly complex data transfer design issues as networks and network devices have evolved into sophisticated systems. An increasing number of network systems now utilize asynchronous transfer mode (ATM) technology, which in many applications provides a more effective way to transfer data across a network.
ATM is a layered architecture allowing multiple services like voice, data, and video to be mixed over the network. Three lower level layers have been defined to implement the features of ATM. An Adaptation Layer assures the appropriate service characteristics and divides all types of data into a 48 byte payload that will make up an ATM cell. An ATM Layer takes the data to be sent and adds a 5 byte header information that assures the cell is sent to the right connection. A Physical Layer defines the electrical characteristics in network interfaces. This layer performs necessary operations to effect transmission of data along the transmission media. However, ATM is not tied to a specific type of physical transport.
A number of protocols exist for transmission of information between the ATM Layer and the Physical layer. One such protocol is the Universal Tests and Operation Physical Interface for ATM (UTOPIA) data path interface. UTOPIA defines the interface between the Physical Layer and upper layer modules such as the ATM Layer. The definition allows a common physical interface in ATM sub-systems across a wide range of speeds and media types. UTOPIA controllers are physical devices that implement the UTOPIA protocol for transmitting information between the physical layer and the ATM layer. A UTOPIA I controller is capable of controlling a single slave device, a UTOPIA II controller is capable of controlling a plurality of slave devices, and a UTOPIA III controller is capable of controlling an even larger number of slave devices.
UTOPIA protocol is often used to transfer data between an ATM card and a line card. Often the DSL line card will be physically located at a significant distance from the ATM card. Communicating data from the ATM card to the DSL line card directly over a cable according to UTOPIA specifications is not currently implemented because of the large transport delays that would be associated with transmitting timing signals and data over a large-length cable. Therefore, current implementations utilize two UTOPIA devices located between the ATM card and the line card to effect such transfer.
These devices consists of a physical device located on the ATM card acting as a UTOPIA slave and a master UTOPIA controller. Data is transferred between the ATM card and the slave physical device according to UTOPIA protocol, and data is transferred from the master UTOPIA controller to the DSL line card according to UTOPIA protocol. However, data is transferred between the slave UTOPIA physical device and the master UTOPIA controller according to any suitable format, and typically in serial format.
Such an implementation for data communication between an ATM card and a physical device, such as a DSL line card, is expensive and consumes more resources than needed.